There is a difference between Canada and other countries. Canada does not have that many people compared to the US, so they wouldn’t need such a large supply to make them happy.
People have to realize that we get from Canada certain medical materials, and there are some Canadian that work in US hospitals. Ontario Canada is closer to large cities such as Detroit and New York than many other areas in the US. With NY already in short supply of medical professionals why anger you neighbours when you might need them.